The project deals with the study of clones of activated T lymphocytes generated from soft agar colony cultures according to methods recently developed in our laboratory. The model of study is the mixed leukocyte culture reaction (MLR) which presents an in vitro model of transplantation immunity. Colonies of alloactivated T lymphocytes are expanded into long term cell cultures with T cell growth factor (TCGF). Studies are designed to determine the functional characteristics of these cell cultures in assays for immunological memory as assessed by primed lymphocyte testing (PLT), cytotoxicity as measured by cell mediated cellular interactions between cells from different colonies and determine their effects on the outcome of the MLR response. Studies are designed to identify serologically defined HLA and T cell specific surface markers on clones and to determine their relationship to functional activities and their role in cellular interactions. These investigations may give us a better understanding of the role of subsets of T cells in the immune response and may lead to the development of a new technology of hemotherapy.